In general, a power source of a hybrid vehicle includes an engine and a driving motor, and the motor supports an output of the engine through assistance of driving power and is charged when the driving power is insufficient. A transmission mounted electric device (TMED) system of the hybrid vehicle is a system that includes a clutch mounted between the engine and the motor, and transmits the power of the engine to the vehicle through the clutch when a torque required by the driver is high.
One of the core controls for improving a fuel ratio of the hybrid vehicle is to control the on and off states of the engine based on conditions, such as a road condition and a state of charge (SOC) of a battery, a vehicle speed, and, for example, may include a lock-up charge control. The lock-up charge control is a prediction control technology that refers to a requirement (e.g., an accelerator pedal sensor (APS) or a brake pedal sensor (BPS)) of the driver, such as a vehicle speed or a SOC, and a purpose of the lock-up charge is to reduce an amount of a non-driven loss fuel by defense of the SOC and frequent switching on/off of the engine.
In other words, when it is not determined that the driver intends to decelerate the vehicle, the lock-up charge control maintains the engine coupling for a specific time period to prevent frequent switching on/off of the engine. However, the prediction control cannot accurately predict all situations. Further, according to the lock-up charge control, an efficiency of the engine deteriorates as compared with a lock-up driving mode due to the operation point of the engine is low.